1. Field of the Invention
This invention relates to clothes washing machines, in particular of the household type, which are provided with a particular water inlet arrangement to fill water into a washing tub.
2. Description of the Related Art
Clothes washing machines are known, particularly of the front-loading type, in which water filling occurs from water delivery mains outside the machine into the washing tub through a water supply conduit. The following components are commonly disposed in the conduit in the given order: an electromagnetic inlet valve, an "air break" (required by applicable regulations), a water dispenser, several compartments containing washing and rinsing products and disposed below the water dispenser and, finally, a conduit conveying the water from said compartments into the washing tub.
Such a type of water fill arrangement is particularly effective if the amount of water to be filled into the tub is not excessively large, i.e. around ten liters, and the detergent is not foaming excessively.
Under such circumstances, in fact, the necessary amount of water is able to reach the washing tub in an acceptably short period of time, although its flow is actually restrained by both said air break and said water dispenser which form hydrodynamic resistances along the flow path. Furthermore, the type of detergent generally used is unlikely to generate foam to any significant extent between said elements due to its inherent properties and to the fact that the amount of water being let into the compartments is quite limited. Above all, said water is let in at a relatively low pressure due to the fact that this takes place downstream of the air break, which is commonly known to cause the water pressure in the downstream flow path to fall off abruptly to almost inappreciable values.
On the other hand, as is required in certain important markets, such as the United States, washing cycles should be kept as short as possible. Further, under-utilization of a relatively high amount of water (i.e. almost three times the typical amount required by European-type washing machines) should be avoided. Also, high-sudsing laundering products are used. Thus, a European-type washing machine presents a number of serious drawbacks.
In the first place, filling in large amounts of water through the normal water inlet circuit including such elements as an air break, water dispenser, product compartments and a siphon, requires correspondingly long periods of time, due mainly to the presence of the siphon. This is clearly contrary to the requirement of short laundering processes prevailing in said marketplace.
Additionally, the particularly high-sudsing property that is peculiar of detergents used in such marketplaces as the United States give rise to considerable foam generation from the siphon and the compartments containing the laundering products. The foam leaking through said siphon and said compartments would eventually flow out of the machine. Furthermore, there may be also direct foam generation in the laundering product compartments when the water is conveyed into them to flush away the product contained therein, and this would of course make things worse.
Finally, the large amount of water used in the process would give rise to a lot of vapors being generated, which would then leak outside, as the foam leaks.
To eliminate such drawbacks, clothes washing machines have been disclosed, for instance in DE 6 919 393, which are provided with a siphon arranged to retain said foam and said vapors.
However, such a solution is not wholly effective in solving the problems, since in all cases the whole amount of water still must flow through the laundering product compartments. Thus, the period of time for the water to flow into the washing tub is unacceptably long as discussed above. Furthermore, such washing machines operate according to the well known principle of recirculation of the washing liquid which requires a greater complexity in construction and higher costs in production.
Clothes washing machines are also known, for instance from DE 1 610 190, in which the water needed for washing is partly filled through the compartments containing the laundering products and partly delivered directly into the washing tub. These washing machines, however, still have a drawback in that they do not actually prevent the foam from possibly reaching up to said compartments. Furthermore, even these washing machines operate according to the aforementioned principle of recirculation of the washing liquid and are therefore encountering the same problems as cited above in connection therewith.
Clothes washing machines are also known, for instance from U.S. Pat. No. 3,258,792, in which the whole amount of water is filled directly into the washing tub, while the laundering products in such washing machines are flushed into the tub through a flow of water being mechanically circulated in a hermetically sealed reservoir containing such products. It will therefore be appreciated that these machines do not eliminate the need to provide a specially arranged recirculation circuit and, as a consequence, still have the aforecited problems of complex construction and expensive manufacturing.